Fractional Flow Reserve (FFR) and Coronary Flow Reserve (CFR) have been originally developed for physiological assessment of coronary artery disease and may hold potential in the management of Peripheral Arterial Disease (PAD) as well. By adapting pressure and flow measurements for the peripheral arteries, clinicians could objectively evaluate stenosis severity, guiding treatment decisions and optimizing outcomes. The aim of this study is to evaluate the diagnostic performance of FFR and vascular Flow Reserve (VFR, aka CFR) for detection of functionally significant peripheral arterial disease and to derive appropriate cut-off values for the prediction of successful immediate and long-term clinical outcomes.